When your army has crossed the border, you should burn your boats and bridges, in order to make it clear to everybody that you have no hankering after home.
When strong, avoid them.
If of high morale, depress them.
Seem humble to fill them with conceit.
If at ease, exhaust them.
If united, separate them.
Attack their weaknesses.
Emerge to their surprise.
It is the rule in war, if our forces are ten to the enemy's one, to surround him; if five to one, to attack him; if twice as numerous, to divide our army into two.